The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Additive manufacturing devices produce three-dimensional parts by sequentially adding materials in a pattern. Some classes of additive manufacturing devices produce polymer parts solidified from a photopolymer resin which has been exposed in a layer-wise fashion to electromagnetic radiation generated by a light source such as a projector. The light source projects a cross sectional image into a build area, solidifying a layer of photopolymer resin into a hardened layer, thereby adding another layer to the object being formed. Ideally, energy output received at each portion of the layer being formed is consistent.
Receiving consistent energy across a layer is essential because the photopolymer resin only hardens into a solid form when exposed to sufficient flux of a specific wavelength of light. If an area to be hardened is not exposed to a sufficiently intense burst of light, it will “undercure” and not solidify in a desirable fashion. Additionally, if an area to be hardened is overexposed, the area will over harden, or “overcure,” which may hamper the building process by, for example, sticking to the build area surface or hardening more resin than required, thereby creating a deformed or failed build. Where uniform light intensity is used to form a layer, undercuring often occurs at the edges of a layer being formed. Undercuring may also occur at fine structures such as thin poles, arms, webbing, and the like.
Inconsistency of curing occurs across a layer because solid portions of a layer, fine portions, and the edges of each layer being formed receive differing amounts of curing energy. This inconsistency occurs because light does not travel through the material being cured in a completely linear fashion. Among other things, there is dispersion, reflection and other optical effects. Additionally, the optical characteristics of the photopolymer resins changes as it cures.
Due to these phenomena, the amount of light energy received by a given portion of a layer being formed is dependent on both the light received directly from the light source and light received from surrounding portions due to dispersion and other effects.
Given the foregoing, what is needed are devices, systems, methods, and computer program products which facilitate uniform curing of layers and other portions of a part being formed by an additive manufacturing device. Furthermore taking into account light energy received from surrounding portions being cured is needed.